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But a low might also be found when hemoglobin synthesis, erythrocytosis and tHb-mass are all entirely normal (or even high), if PV is disproportionately expanded. 14 Traditionally, this has been considered the result of a reduced tHb-mass.
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Anemia is common in diseases such as cancer, 11 inflammatory bowel disease (IBD), 12 chronic heart failure (CHF), 8 chronic kidney disease (CKD) 13 and chronic liver disease (CLD).
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Likewise, alterations in the relationship between plasma volume and tHb-mass might strongly influence in disease states. Then, in 2001, Heinicke and colleagues demonstrated that tHb-mass was increased by some 35% in elite endurance athletes, matching that in the untrained only because PV was expanded to a similar degree. Thus, the circulating hemoglobin concentration in athletes matches that in sedentary individuals, meaning that a contribution of increased red cell oxygen carriage to elite performance was largely dismissed.
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#Hemoglobin and hematocrit levels dropping without a reason drivers
However, such assessment may be important if the drivers of an altered, and the appropriate therapeutic response, are to be truly understood. In clinical practice these factors are not routinely considered separately, or measured, and even in experienced hands their estimation is not trivial. The concentration of circulating hemoglobin will depend not just on the total circulating quantity of hemoglobin (total hemoglobin mass, (tHb-mass), but also on the volume of plasma (plasma volume, PV) in which it is suspended. However, it is now becoming clear that this approach may be somewhat simplistic. Once anemia is identified, the cause of impaired hemoglobin synthesis or erythrocytosis, or of increased red cell loss or destruction, is often sought and treatment (either of the underlying cause, or through the administration of packed donor red cells) initiated. 9 4įor these reasons, circulating hemoglobin concentrations are routinely measured in clinical practice. Given its diverse etiology, anemia is common, affecting over 1.6 billion people worldwide, 2 and is associated with impaired functional capacity, reduced quality of life, 3 and poorer outcome in diverse disease states. Such reductions can result from the destruction or loss of erythrocytes or a failure of their production, or from impaired hemoglobin synthesis. Measurement of total hemoglobin mass and plasma volume is now simple, cheap and safe, and its more routine use is advocated.Īnemia is defined as a reduction in the circulating concentration of hemoglobin () to < 120 g.l in non-pregnant females and < 130 g.l in males. The traditional inference that anemia generally reflects hemoglobin deficiency may be misleading, potentially resulting in inappropriate tests and therapeutic interventions to address ‘hemoglobin deficiency’ not ‘plasma volume excess’. Exemplar patients with identical (normal or raised) total hemoglobin masses were diagnosed as profoundly anemic (or not) depending on differences in plasma volume that had not been measured or even considered as a cause. Here, hemoglobin mass explained little of the variance in its concentration (adjusted R 2=0.109 and 0.052 P=0.11 and 0.16), whilst plasma volume did (R 2 change 0.724 and 0.805 in heart and liver disease respectively, P<0.0001). However, they were poorly related in liver disease (r=0.410, P=0.11) and heart failure patients (r=0.312, P=0.16). Hemoglobin mass correlated well with its concentration in the healthy, surgical and inflammatory bowel disease groups (r=0.687–0.871, P<0.001). But does this matter? We explored this issue in patients, measuring hemoglobin concentration, total hemoglobin mass (optimized carbon monoxide rebreathing method) and thereby calculating plasma volume in healthy volunteers, surgical patients, and those with inflammatory bowel disease, chronic liver disease or heart failure. Rarely is a rise in plasma volume relative to circulating total hemoglobin mass considered as a cause. In practice, clinicians generally consider anemia (circulating hemoglobin concentration < 120 g.l −1 in non-pregnant females and < 130 g.l −1 in males) as due to impaired hemoglobin synthesis or increased erythrocyte loss or destruction.